Actually it was a hoax.
I read an article by two professional genealogists and they said it did not even equal amateur standards. Most of the characters did exist but were not Haley’s relatives.
They also mentioned that he did an especially egregious fraud by claiming kinship to the Lea family of Virginia when he wasn’t.
He plagiarized the book from someone else, so obviously it wasn’t his family. It was the rightful intellectual property of another man.